Porcine reproductive and respiratory syndrome (PRRS) is one of the most economically important diseases in swine worldwide. The causal agent of the syndrome, porcine reproductive and respiratory syndrome virus (PRRSV), is a single stranded RNA virus that is classified as a member of the family Arteriviridae. Regarding genetic diversity, there are two major prototypes of PRRSV, the European isolate and the North American isolate. Clinical signs of PRRS include reproductive failure, post-weaning pneumonia, growth reduction, and increased mortality. A presumptive diagnosis of PRRS can be made on the basis of herd performance and clinical signs. A definitive diagnosis requires either detection of viral antigen, viral genomic material, isolation of the virus or detection of PRRSV-antibodies. Several methods of eradication have been shown effective in eliminating PRRSV from positive herds. It is important to determine the pattern of viral infection within a herd in order to decide which methods of control have the greatest chance of success.
The Austrian animal health service (TGD) developed the PRRS monitoring programme Programm zur Überwachung von PRRS in österreichischen Herdebuchzuchtbetrieben, which started in 2003. In 2006, the Upper Austrian TGD initiated the programme Stabilisierung der Tiergesundheit in der oberösterreichischen Ferkelproduktion. Due to the periodical serological monitoring of these two programmes, data about the PRRS situation of a large number of Austrian swine production sites were available for the first time. The aim of this paper was to evaluate the structure and the sample size of these two TGD programmes and propose recommendations for possible improvements.